I never have had this problem before, after autoupdating to 8.8.1 the options window is too large to be able to access any settings, normally I go ahead and clear FEBE after an update and then redo my settings, but I can't as there is no way to resize the window and I am already at highest resolution. I had searched the forum for solutions but only saw an older post that had to do with editing Firefox json files and I am not very comfortable with that, plus I have no other problems with FEBE or Firefox other than the size of the FEBE options window. Any advice would be appreciated, thanks.

That worked, thanks very much! hopefully whatever broke in Firefox will be fixed in the next iteration. It's only FEBE's option window affected though, none of my other addons option windows have been resized to unusability, and of course FEBE is the most useful addon.

not only is this still a problem in Firefox 55, but now I get the unresponsive script error and febe will not run at the scheduled time, and I have uninstalled and reinstalled and cleared all preferences too many times for this to continue

Sorry, but Mozilla has made too many changes to Fx for me to keep up with. It seems every new release breaks something. Since FEBE (and all other 'legacy' extensions) will no longer work with Fx v57 coming this November, I will not be maintaining it for Fx. I will, however, continue to support FEBE for Fx clones (like Pale Moon).

FEBE cannot be re-written with WebExtensions, which is the only platform Mozilla will allow for add-ons starting with v57.